Polymer scale preventive agent

Abstract: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising an alkaline solution containing a condensation product of (A) a heterocyclic compound having at least two amino groups, and (B) a quinone compound. This agent is used for forming a coating on the inner wall, etc. of a polymerization vessel. Such a vessel is effective in preventing polymer scale deposition, not only on the areas located in the liquid-phase region but also on the areas around the interface between the gas and liquid phases in the vessel, and useful in producing a polymer that shows few fish eyes and good whiteness when formed into sheets or the like.

Description: The present invention relates to a polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, a polymerization vessel effective in preventing polymer scale deposition, and a process for producing a polymer using the same. Heretofore, methods for polymerization of a monomer having an ethylenically unsaturated double bond have been known, such as suspension, emulsion, solution, gas phase and bulk polymerization processes and the like. In any of these polymerization processes, polymer scale is liable to be deposited on the areas with which the monomer comes into contact, such as inner walls, stirring equipment and so on of a polymerization vessel. The deposition of the polymer scale results in disadvantages that the yield of the polymer and cooling capacity of the polymerization vessel are lowered, and that the polymer scale may peel off and mix into a polymeric product, thereby impairing the quality of formed products obtained by processing the polymeric product. In addition, removal of deposited polymer scale is very laborious and time-consuming. Further, the polymer scale contains unreacted monomers and, therefore, may cause physical disorders in the operators, which has been a very serious problem in recent years. For preventing polymer scale deposition on the polymerization vessel inner wall and so forth, methods have been known, for example, a method in which a polymer scale preventive agent comprising a polar organic compound such as amine compounds, quinone compounds, aldehyde compounds, etc. is applied to the polymerization vessel inner wall and so on to form a coating and a method in which such compounds are added to an aqueous medium (Japanese Patent Publication (KOKOKU) No. 45-30343 (1970)), as practiced in some instances of suspension polymerization of vinyl chloride. However, these methods have the disadvantage that, although the polymer scale preventive effect is exhibited while polymerization is repeated for up to about 5 or 6 batches, the effect diminishes if the number of repeated batches of polymerization exceeds 5 or 6 (that is, the scale preventive effect is poor in durability). The disadvantage is emphasized particularly where a water-soluble catalyst is used for polymerization, and, in this point, the polymer scale prevention according to these methods is unsatisfactory industrially. For overcoming the above disadvantage, Japanese Pre-examination Patent Publication (KOKAI) No. 53-13689 (1978) proposes a method in which the inner wall, etc. of a polymerization vessel are coated with a polymer scale preventive agent comprising a condensation product of an aromatic amine compound as an effective constituent . Where the polymer scale preventive agent is applied to the areas with which monomers come into contact, such as the inner wall surface of a polymerization vessel, and a coating is thereby formed, it is possible to repeat about 100 to 200 batches of polymerization without causing deposition of polymer scale on the areas located in the liquid-phase region inside the polymerization vessel. Besides, even in the above-mentioned case where a water-soluble catalyst is used, deposition of polymer scale in the liquid-phase region is similarly prevented. However, after the coating of the polymer scale preventive agent comprising a condensation product of an aromatic amine compound as its effective constituent is formed, there still remains a drawback that polymer scale deposition may occur on the areas around the interface between the liquid phase and the gas phase located at an upper portion of the interior of the polymerization vessel. Once polymer scale deposition occurs on the areas around the interface between the gas and liquid phases, the deposited scale will grow gradually as polymerization runs are repeated, and at last it may peel off to be incorporated into the polymeric product. If the polymeric product with the polymer scale thus mixed therein is processed into formed products such as sheets, the polymer scale causes generation of many fish eyes in the formed products, thereby lowering seriously the quality of the formed products. Besides, the polymeric product obtained upon polymerization is required to have a high whiteness. That is, when a polymeric product is formed into a sheet without any addition of a coloring agent, the resulting formed product is more or less colored and such coloration, called initial coloration, is desired to be as slight as possible. However, the aforesaid coating of the polymer scale preventive agent which contains a condensation product of an aromatic amine compound may peel off or dissolve in the polymerization mass, to be incorporated into the polymeric product; in such a case, the resulting formed products will have a lowered whiteness, i.e., a higher initial coloration. In the US-A-4,970,278 is described a polymer scale deposition on polymerization reactor inside surfaces in the polymerization of a monomer or monomers having an ethylenic double bond and or a monomer or monomers having diolefinic double bonds is prevented, peelability or removability of polymer scales deposited on such surface, if any, is improved and the scale inhibitor adherence to the wall surface of the glass-lined polymerization reactors is improved by coating the inside surfaces of the reactor in advance with a coating composition comprising a quinone-amine compound having a molecular weight of at least 3,000 as obtained by subjecting at least one aromatic diamine and at least one aromatic quinone to addition reaction in at least one solvent having a solubility parameter of 8.5 to 24.0 and/or a reduced form of said quinone-amine compound and at least one silica organosol or a mixture of at least one silica organosol and at least one alkyl silicate to thereby form a hydrophilic coat film on the surfaces. Accordingly it is an object of the present invention to provide a polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond that can prevent effectively the deposition of polymer scale, not only on the areas in the liquid-phase region but also on the areas around the interface between the gas and liquid phases inside a polymerization vessel, and that makes it possible to produce a polymer having a very small number of fish eyes and slight initial coloration when processed into formed products such as sheets; and a polymerization vessel and a process for producing a polymer which utilize the polymer scale preventive agent. The present invention provides, as a means of achieving the above object, a polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond on the basis of a condensation product of a heterocyclic compound having at least two amino groups, and a quinone compound, characterized by an alkaline solution with a pH of 7.5 to 13.5 containing a mixed solvent of water with an organic solvent miscible with water, said organic solvent being present in an amount of not more than 50% by weight based on said mixed solvent, and containing a condensation product prepared by a reaction of the heterocyclic compound with the quinone compound in a suitable solvent at a temperature of room temperature to 200°C for 0.5 to 100 hours. The present invention also provides a polymerization vessel for polymerizing a monomer having an ethylenically unsaturated double bond on the basis of a condensation product of a heterocyclic compound having at least two amino groups, and a quinone compound, characterized by a coating on its inner wall surfaces, wherein said coating has been formed by applying an alkaline solution with a pH of 7.5 to 13.5 containing a mixed solvent of water with an organic solvent miscible with water, said organic solvent being present in an amount of not more than 50% by weight based on said mixed solvent, and containing a condensation product prepared by a reaction of the heterocyclic compound with the quinone compound in a suitable solvent at a temperature of room temperature to 200°C for 0.5 to 100 hours, followed by drying. Further, the present invention provides a process for producing a polymer of a monomer having an ethylenically unsaturated double bond on the basis of a condensation product of a heterocyclic compound having at least two amino groups, and a quinone compound, characterized by polymerizing the monomer in a polymerization vessel having a coating on its inner wall surfaces, wherein said coating has been formed by applying an alkaline solution with a pH of 7.5 to 13.5, followed by drying. According to the present invention, deposition of polymer scale in a polymerization vessel can be effectively prevented, not only on the areas in the liquid-phase region but also on the areas around the interface between the gas phase and the liquid phase. Therefore, where polymerization is conducted by applying the present invention, the operation of removing polymer scale need not be performed every run of polymerization, and productivity is thereby improved. In addition, the polymer obtained by application of the present invention can be processed into formed products such as sheets which have very few fish eyes. Furthermore, the formed products have good quality in regard of initial coloration. More specifically, the formed products have a luminosity index (L value) in the Hunter's color difference equation described in JIS Z 8730 (1980) of, for example, 70 or more in the case of vinyl chloride polymers and 80 or more in the case of SBR. Heterocyclic compound (A) The heterocyclic compound having at least two amino groups (-NH 2 ) includes, for example, the compounds having the following general formula (1): (R 1 ) k X(NH 2 ) 2 wherein R 1 is -OH, -COOH, -SO 3 H, -NH 2 , -Cl, -Br, -I, -SH, -NO 2 , -COCH 3 , -OCH 3 , -N(CH 3 ) 2 , -C 6 H 5 or an alkyl group having 1 to 3 carbon atoms, and where a plurality of R 1 groups are present, they may be the same or different from each other, k is an integer of 0 to 9, and X is a heterocyclic group with a valence of k+2. The heterocyclic group represented by X herein refers to a group which has at least one heterocycle in its molecule. The heterocycle may be condensed with a carbon homocycle and/or another heterocycle. The heterocyclic group includes, for example, those which are each derived from a heterocyclic compound such as pyrrole, indole, isoindole, carbazole, porphyrin, oxazole, thiazole, benzothiazole, imidazole, pyrazole, triazole, thiadiazole, pyridine, pyrimidine, quinoline, acridine, phenanthridine, phenanthroline, naphthyridine, furan, benzofuran, pyran, pyrrone, benzopyrylium, cumarin and xanthone, by removal of k+2 hydrogen atoms attached to a ring of said compound. Specific examples of the heterocyclic compound having at least two amino groups include the followings: Pyrrole compounds such as 2,4-diaminopyrrole, 2,5-diaminopyrrole; Indole compounds such as 2,5-diaminoindole, 3,5-diaminoindole; Isoindole compounds such as 1,3-diaminoisoindole, 4,7-diaminoisoindole; Carbazole compounds such as 2,6-diaminocarbazole, 3,6-diaminocarbazole; Oxazole compounds such as 2,4-diaminooxazole, 4-acetyl-2,5-diaminooxazole; Thiazole compounds such as 2,4-diaminothiazole, 2,4-diamino-5-methylthiazole, 2,4-diamino-5-phenylthiazole, 2,4-diaminothiazole-5-carboxylic acid, 2,4-diaminothiazole-5-sulfonic acid; Benzothiazole compounds such as 2,4- and 2,5-diaminobenzothiazoles, 2,4-diaminobenzothiazole-6-carboxylic acid, 2,4-diaminobenzothiazole-6-sulfonic acid; Imidazole compounds such as 2,4-diaminoimidazole, 2,5-diaminoimidazole; Pyrazole compounds such as 3,4-diaminopyrazole, 3,5-diaminopyrazole; Thiadiazole compounds such as 2,5-diamino-1,3,4-thiadiazole; Pyridine compounds such as 2,3-, 2,5-, 2,6- and 3,4-diaminopyridine, 4-hydroxy-2,6-diaminopyridine, 4-chloro-2,6-diaminopyridine; Pyrimidine compounds such as 2,4-, 2,6- and 4,6-diaminopyrimidine, 2,4,5-triaminopyrimidine, 4,5,6-triaminopyrimidine, 2,4-diamino-6-hydroxypyrimidine, 4,6-diamino-2-hydroxypyrimidine, 2,6-diamino-4-hydroxypyrimidine, 2,4-diaminopyrimidine-5-carboxylic acid, 2,4-diaminopyrimidine-6-carboxylic acid, 4,6-diaminopyrimidine-2-carboxylic acid, 2,6-diaminopyrimidine-4-carboxylic acid, 4,6-diaminopyrimidine-2-sulfonic acid, 2,6-diaminopyrimidine-4-sulfonic acid, 2,4-diaminopyrimidine-6-sulfonic acid, 2,4,5-triamino-6-hydroxypyrimidine, 2,4-diamino-6-mercaptopyrimidine, 4,6-diamino-2-mercaptopyrimidine; Quinoline compounds such as 2,3-, 2,4-, 3,4-, 4,6-, 4,8-, 5,6-, 5,7-, 5,8-, 6,8- and 7,8-diaminoquinolines, 5,8-diamino-6-methoxyquinoline, 5,8-diaminoquinoline-2-carboxylic acid, 5,8-diaminoquinoline-2-sulfonic acid, 5,8-diamino-6-hydroxyquinoline; Acridine compounds such as 1,6-, 1,7-, 1,9-, 2,4-, 2,5-, 2,6-, 2,7-, 2,9-, 3,5-, 3,6-, 3,8-, 3,9- and 4,9-diaminoacridines, 4,9-diamino-2-hydroxyacridine, 4,9-diaminoacridine-2-carboxylic acid, 4,9-diaminoacridine-2-sulfonic acid; Phenanthridine compounds such as 3,6-diaminophenanthridine, 6,9-diaminophenanthridine; Phenanthroline compounds such as 2,4-diamino-1,10-phenanthroline, 2,9-diamino-1,10-phenanthroline; Naphthyridine compounds such as 2,6-diamino-1,5-naphthyridine, 2,4-diamino-1,8-naphthyridine; Furan compounds such as 2,4-diaminofuran, 2,5-diaminofuran; Benzofuran compounds such as 3,6-diaminobenzofuran, 4,6-diaminobenzofuran; Pyran compounds such as 2,6-diaminopyran, 3,6-diaminopyran; Pyrrone compounds such as 3,6-diamino-α-pyrrone, 2,6-diamino-γ-pyrrone; Benzopyrylium compounds such as 2,7-diamino-4-benzopyrylium chloride, 4,7-diamino-2-benzopyrylium chloride; Cumarin compounds such as 3,4-diaminocumarin, 5,7-diaminocumarin; and Xanthone compounds such as 1,6-diaminoxanthone, 2,7-diaminoxanthone . Among the components above, preferred are pyridine compounds, acridine compounds, pyrimidine compounds, thiazole compounds and quinoline compounds which each have at least two amino groups. Among the above compounds, particularly preferred are 2,6-diaminopyridine, 3,6-diaminoacridine, 1,6-diaminoacridine, 3,9-diaminoacridine, 4,9-diamino-2-hydroxyacridine, 4,9-diaminoacridine-2-sulfonic acid, 2,4-diamino-6-hydroxypyrimidine, 4,6-diaminopyrimidine, 2,4,5-triaminopyrimidine, 2,4-diaminopyrimidine-5-carboxylic acid, 4,6-diaminopyrimidine-2-sulfonic acid, 2,4-diaminothiazole, 2,4-diaminothiazole-5-carboxylic acid, 5,8-diaminoquinoline and 4,8-diaminoquinoline. These compounds may be used either singly or in combination of two or more. Quinone (B) The quinone compound includes, for example, the benzoquinone compounds of the following general formulas (2) and (3): wherein in the formulas (2) and (3), (R 2 )'s may be the same or different and each are -H, -NH 2 , -Cl, -Br, -OH, -NO 2 , -OCH 3 , -COCH 3 , -N(CH 3 ) 2 , -COOH, -SO 3 H or an alkyl group having 1 to 3 carbon atoms; and the naphthoquinone compounds of the following general formulas (4) and (5): wherein in the formulas (4) and (5), (R 2 )'s may be the same or different and each are as defined above, and (R 3 )'s may be the same or different and each are -H, -Cl, -Br, -OH, -OCH 3 , -COCH 3 , -CH 3 , -COOH or -SO 3 H. The benzoquinone compounds of the above general formulas (2) and (3) include, for example, o- and p-benzoquinones, hydroxy-p-benzoquinone, chloro-p-benzoquinone, bromo-p-benzoquinone, duroquinone and chloranil. The naphthoquinone compounds of the above general formulas (4) and (5) include, for example, 6-methyl-1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, 2-hydroxy-1,4-naphthalenedione, juglone, plumbagin, α-naphthoquinone and β-naphthoquinone. Among the compounds above, preferred are o- and p-benzoquinone, α-naphthoquinone, β-naphthoquinone and 2-hydroxy-1,4-naphthalenedione. The aforementioned quinone compounds may be used either singly or in combination of two or more. Condensation reaction The condensation product of (A) and (B) which is the indispensable constituent of the polymer scale preventive agent according to the present invention, can be prepared by reacting the two components with each other in the suitable solvent, optionally in the presence of a catalyst as required, normally at a temperature of room temperature to 200°C for 0.5 to 100 hours, and preferably at room temperature to 150°C for 3 to 30 hours. Since the quinone compound acts also as a condensation catalyst, it is normally unnecessary to add other condensation catalyst to the reaction system. However, other condensation catalysts may be added, as required. The other condensation catalysts which can be added include, for example, elemental or molecular simple-substance halogens such as iodine, bromine, chlorine and fluorine; oxo-acids and oxo-acid salts of halogen, such as iodic acid, periodic acid, potassium periodide and sodium perchlorate; inorganic peroxides such as hydrogen peroxide, sodium peroxide, potassium persulfate and ammonium persulfate; organic peroxides such as peracetic acid, benzoyl peroxide, cumene hydroperoxide, perbenzoic acid and p-menthane hydroperoxide; chlorides and sulfates of a metal selected from the group consisting of iron and copper, such as ferrous chloride, ferric chloride, copper sulfate and cuprous chloride; azo compounds such as α,α'-azobisisobutyronitrile and α,α'-azobis-2,4-dimethylvaleronitrile; aromatic nitro compounds such as o-, m- and p-oxynitrobenzenes, o-, m- and p-nitroanisoles, o-, m- and p-chloronitrobenzenes, o-, m- and p-nitrobenzoic acids, o-, m- and p-nitrobenzenesulfonic acids. As a solvent for carrying out the above condensation reaction, organic solvents such as alcohols, ketones and esters can be used, which are miscible with water. Preferable examples of the organic solvents miscible with water include alcohols such as methanol, ethanol and propanol, ketones such as acetone and methyl ethyl ketone, and esters such as methyl acetate and ethyl acetate, among which particularly preferred are alcohols. Further, mixed solvents of water and such an organic solvent miscible with water as above-mentioned may also be used. The medium for condensation reaction normally has a pH of 1 to 13, and pH adjusters may be used without any particular restrictions. The relative amounts of the two compounds to be brought into the condensation reaction depend on the kinds of the compounds and solvent used, reaction temperature and reaction time. Normally, it is preferable to use the quinone in an amount of 0.01 to 10 parts by weight, more preferably from 0.1 to 5 parts by weight, per part by weight of the heterocyclic compound. If the amount of the heterocyclic compound is too large or too small, the resulting condensation product has a lower effect in preventing polymer scale deposition. Polymer scale preventive agent comprising an alkaline solution The polymer scale preventive agent according to the present invention comprises an alkaline solution containing the condensation product of the above-described components. The polymer scale preventive agent is applied to inner wall surfaces of a polymerization vessel and is dried to form a coating, whereby polymer scale can be prevented from being deposited on the polymerization vessel inner wall. To prepare the polymer scale preventive agent, the solution containing the condensation product obtained by the condensation reaction as above is admixed with a solvent (which will be described below) as required, and the pH of the resulting solution is controlled to the alkaline side. Alternatively, the polymer scale preventive agent may be prepared by putting the condensation product-containing solution into cold water to precipitate the condensation product, then separating the precipitate by filtration and drying it, adding the solvent (described below) to the dried precipitate, and controlling the pH of the resulting solution to the alkaline side. Because the polymer scale preventive agent of the present invention is made alkaline, the solubility of the condensation product in the solvent is improved and a uniform solution can be obtained. Therefore, by applying the polymer scale preventive agent to the polymerization vessel inner wall surfaces, an improved scale preventive effect can be obtained. The pH of the inventive polymer scale preventive agent ranges from 7.5 to 13.5, more preferably from 8.0 to 13.5. For pH adjustment, alkaline compounds can be used, for example, alkali metal compounds such as LiOH, NaOH, KOH, Na 2 CO 3 , and Na 2 HPO 4 , ammonium compounds such as NH 4 OH, organic amine compounds such as ethylenediamine, monoethanolamine, diethanolamine and triethanolamine. The solvent for use in preparation of the polymer scale preventive agent of the present invention includes, for example, water; alcohol solvents such as methanol, ethanol, propanol, butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 3-methyl-1-butanol, 2-methyl-2-butanol and 2-pentanol; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ester solvents such as methyl formate, ethyl formate, methyl acetate, ethyl acetate and methyl acetoacetate; ether solvents such as 4-methyldioxolan and ethylene glycol diethyl ether; furans; aprotic solvents such as dimethylformamide, dimethyl sulfoxide and acetonitrile. These may be used either singly or as a mixed solvent of two or more thereof on a case-by-case basis. The organic solvents miscible with water include, for example, alcohol solvents such as methanol, ethanol and propanol; ketone solvents such as acetone and methyl ethyl ketone; and ester solvents such as methyl acetate and ethyl acetate. The mixed solvents of water and an organic solvent miscible with water preferably contain the organic solvent in such an amount that there is no fear about inflammation, explosion and safety in handling is ensured as to virulence . Specifically, the amount of the organic solvent is not more than 50% by weight, a more preferable amount being not more than 30% by weight. Other ingredients In order to further enhance the polymer scale preventive effect, it is preferable to add to the above-described agent at least one member selected from the group consisting of (C) a water-soluble polymeric compound, (D) an inorganic colloid and (E) an alkali metal silicate. These additives (C) to (E) enhance the scale preventive effect, presumably by interacting with the condensation product in such a manner as to improve the hydrophilicity of the surfaces being coated (in the case of the water-soluble polymeric compound (C)) or to improve adhesion to the polymerization vessel wall and so on (in the cases of the inorganic colloid (D) and the alkali metal silicate (E)). (C) Water-soluble polymeric compound The water-soluble polymeric compounds (C) which can be added to the polymer scale preventive agent include, for example, nonionic polymeric compounds such as gelatin and casein ; anionic polymeric compounds such as polyacrylic acid, polystyrenesulfonic acid, carboxymethyl cellulose and alginic acid; cationic nitrogen-containing polymeric compounds such as polyvinyl pyrrolidone and polyacrylamide; hydroxyl group-containing polymeric compounds such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose and pectin. Among the water-soluble polymeric compounds above-mentioned, preferred are gelatin, casein, polyacrylic acid, carboxymethyl cellulose, polyvinyl pyrrolidone and pectin. The water-soluble polymeric compounds (C) may be used either singly or in combination of two or more. The component (C) is added in an amount of normally 1 to 1000 parts by weight, preferably 5 to 200 parts by weight, per 100 parts by weight of the condensation product. (D) Inorganic colloid The inorganic colloids (D) which can be added to the polymer scale preventive agent are those obtained by a condensing method or a dispersing method using water as a dispersion medium, with the colloidal particles ranging from 1 to 500 mµ in size. Specifically, the applicable inorganic colloids include, for example, colloids of an oxide, a hydroxide or a mixture thereof, the oxide and hydroxide being those of a metal such as aluminum, thorium, titanium, zirconium, antimony, tin, iron and the like; colloids of tungstic acid, vanadium pentoxide, gold and silver; silver iodide sol; colloids of selenium, sulfur and silica. Among the inorganic colloids above, preferred are colloids of an oxide, a hydroxide or a mixture thereof, the oxide and hydroxide being those of a metal selected from the group consisting of aluminum, titanium, zirconium, tin and iron; and colloidal silica. The inorganic colloids (D) are added in an amount of normally 1 to 1000 parts by weight, preferably 5 to 500 parts by weight, per 100 parts by weight of the condensation product . (E) Alkali metal silicates The alkali metal silicates (E) which can be added to the polymer scale preventive agent of the present invention include, for example, metasilicates (M 2 SiO 3 ), orthosilicates (M 4 SiO 4 ), disilicates (M 2 Si 2 O 3 ), trisilicates (M 3 Si 3 O 7 ) and sesquisilicates (M 4 Si 3 0 10 ) of alkali metals such as lithium, sodium and potassium (wherein M stands for an alkali metal such as lithium, sodium and potassium); and water glass. The alkali metal silicates (E) may be used either singly or in combination of two or more. The component (E) is added in an amount of normally 1 to 1000 parts by weight, preferably 5 to 500 parts by weight, per 100 parts by weight of the heterocyclic compound. Where the component (D) and the component (E) are used in combination, the total amount of the components (D) and (E) is preferably 1 to 1000 parts by weight, more preferably 5 to 500 parts by weight, per 100 parts by weight of the For best improving the polymer scale preventing effect, it is preferable to use a combination of the water-soluble polymeric compound (C) with the inorganic colloid (D) or a combination of the water-soluble polymeric compound (C) with the alkali metal silicate (E). Where the components (C) and (D) are used in combination, the amount of the component (D) is preferably 5 to 3000 parts by weight, more preferably 50 to 1000 parts by weight, per 100 parts by weight of the component (C). Where the components (C) and (E) are used in combination, the component (E) is preferably used in an amount of 5 to 3000 parts by weight, more preferably 50 to 1000 parts by weight, per 100 parts by weight of the component (C). The concentration of the condensation product in the coating liquid is not particularly limited, as long as the total coating weight described later can be obtained. Normally, the concentration of the condensation product is on the order of 0.001 to 5% by weight, a preferable concentration being on the order of 0.01 to 1% by weight. Where the components (C) to (E) are added, the total concentration of the condensation product and these components (C) to (E) is preferably on the order of 0.1 to 20% by weight, more preferably on the order of 0.2 to 6% by weight. Formation of coating To form a coating on inner wall surfaces of a polymerization vessel using the polymer scale preventive agent prepared as above-described, first the agent is applied to the inner wall surfaces of the polymerization vessel. Then, the applied agent is dried sufficiently at a temperature ranging, for example, from room temperature to 100°C, optionally followed by washing with water. The polymer scale preventive agent is preferably applied to not only the inner wall surfaces of a polymerization vessel but also other areas with which the monomer comes into contact during polymerization, for example, stirring blades, stirring shaft, baffles, condensers, headers, search coil, bolts and nuts. More preferably, for formation of the coating, the polymer scale preventive agent is applied to areas with which the monomer does not come into contact during polymerization but on which polymer scale may be deposited, for example, the inner surfaces of equipment and pipes of an unreacted monomer recovery system. Specifically, such areas include the inner surfaces of monomer distillation columns, condensers, monomer stock tanks and valves. The method of applying the polymer scale preventive agent to the inner wall surfaces of a polymerization vessel is not particularly restricted, and includes, for example, brush coating, spray coating, a method by filling the polymerization vessel with the polymer scale preventive agent followed by withdrawal thereof, and the automatic coating methods as disclosed in Japanese Pre-examination Patent Publication (KOKAI) Nos. 57-61001 (1982) and 55-36288 (1980), Japanese Patent Publication (KOHYO) Nos. 56-501116 (1981) and 56-501117 (1981), and Japanese Pre-examination Patent Publication (KOKAI) No. 59-11303 (1984). The method of drying wet coated surfaces provided by application of the polymer scale preventive agent, is not restricted, either. For example, the following methods can be used: a method in which, after the agent is applied, hot air with a suitable elevated temperature is blown to the coated surface; a method in which the inner wall surfaces of a polymerization vessel and the surfaces of other parts to be coated are preliminarily heated, for example, to a temperature of 30 to 80°C, and the polymer scale preventive agent is directly applied to the heated surfaces; and so on. After dried, the coated surfaces are washed with water if necessary. The coating obtained in this manner has a total coating weight after dried of normally 0.001 to 5 g/m 2 , preferably 0.05 to 2 g/m 2 . The formed coating has good durability and retains the polymer scale-preventing action; therefore, the above-described coating operation may not necessarily be carried out every batch of polymerization. Accordingly, productivity is improved. Polymerization After the formation of the coating on the inner wall surfaces of a polymerization vessel, and preferably also on other areas with which monomer may come into contact during polymerization by the coating operation as above, polymerization is carried out in accordance with conventional procedures. That is, a monomer having an ethylenically unsaturated double bond, a polymerization initiator (catalyst), and optionally a polymerization medium such as water , a disperging agent such as suspending agents, solid dispersing agents, nonionic or anionic emulsifying agents are charged into the polymerization vessel, and then polymerization is carried out according to conventional procedures. The monomers having an ethylenically unsaturated double bond which can be polymerized by applying the process of the present invention include, for example, vinyl halides such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid, methacrylic acid, and their esters and salts; maleic acid, fumaric acid, and their esters and anhydrides; diene monomers such as butadiene, chloroprene, and isoprene; styrene; acrylonitrile; vinylidene halides; vinyl ethers . These monomers may be used either singly or in combination of two or more. There are no particular restrictions on the type of polymerization to which the process according to the present invention can be applied. That is, the process of the present invention is effective in any of such polymerization types as suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization, and gas phase polymerization. Particularly, the process of the present invention is more suited to polymerizations in an aqueous medium, such as suspension polymerization and emulsion polymerization. In the following, taking the cases of suspension polymerization and emulsion polymerization as an example, general procedures of polymerization will be described. First, water and a dispersing agent are charged into a polymerization vessel. Subsequently, the polymerization vessel is evacuated to reduce the internal pressure to a value of 0.1 to 760 mmHg, and a monomer is then charged (whereupon the internal pressure usually takes a value of 0.5 to 30 kgf/cm 2 .G). A polymerization initiator is charged into the vessel before and/or after charging the monomer. Subsequently, polymerization is carried out at a reaction temperature of 30 to 150°C. During the polymerization, one or more of water, a dispersing agent and a polymerization initiator may be added, if necessary. Reaction temperature during the polymerization is different depending on the kind of monomer to be polymerized. For example, in the case of polymerizing vinyl chloride, polymerization is carried out at 30 to 80°C; in the case of polymerizing styrene, polymerization is carried out at 50 to 150°C. The polymerization may be judged to be completed when the pressure inside the polymerization vessel has fallen to a value of 0 to 7 kgf/cm 2 .G or when cooling water which is let flow into and out of a jacket provided around the polymerization vessel has come to show approximately equal inlet and outlet temperatures (i.e., when liberation of heat due to polymerization reaction has subsided). The amounts of the water, dispersing agent and polymerization initiator to be charged for polymerization are 20 to 500 parts by weight, 0.01 to 30 parts by weight, and 0.01 to 5 parts by weight, respectively, per 100 parts by weight of the monomer. In solution polymerization, an organic solvent such as toluene, xylene, pyridine is used as the polymerization medium, in place of water. A dispersing agent may be used, if necessary. The other conditions for polymerization are generally the same as those described for suspension and emulsion polymerizations. In bulk polymerization, after a polymerization vessel is evacuated to a pressure of 0.01 mmHg to 760 mmHg, a monomer and a polymerization initiator are charged into the polymerization vessel, and then polymerization is carried out at a reaction temperature of -10°C to 250°C. For example, the reaction temperature is 30 to 80°C for polymerization of vinyl chloride, and is 50 to 150°C for polymerization of styrene. Where polymerization is carried out by applying the process of the present invention, it is possible to prevent polymer scale from being deposited, regardless of the materials of the inner wall of a polymerization vessel. For example, where the polymerization vessel is made of a stainless steel or other steel as well as where the polymerization vessel is a glass-lined one or the like, the polymer scale deposition can be prevented from occurring during polymerization. Those additive materials which are conventionally added in polymerization systems can be used without any limitations. That is to say, the process of the present invention can effectively prevent polymer scale deposition in polymerization systems which may contain additive materials including, for example, polymerization initiators such as t-butyl peroxyneodecanoate, bis(2-ethylhexyl) peroxydicarbonate, 3,5,5-trimethylhexanoyl peroxide, α-cumyl peroxyneodecanoate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl peroxypivalate, bis(2-ethoxyethyl) peroxydicarbonate, benzoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, α,α'-azobisisobutyronitrile, α,α'-azobis-2,4-dimethylvaleronitrile, potassium peroxodisulfate, ammonium peroxodisulfate, p-menthane hydroperoxide; suspending agents comprised of, for example, natural or synthetic polymeric compounds such as partially saponified polyvinyl alcohols, polyacrylic acids, vinyl acetate/maleic anhydride copolymers, cellulose derivatives (e.g. hydroxypropyl methyl cellulose), gelatin; solid dispersing agents such as calcium phosphate, hydroxyapatite; nonionic emulsifying agents such as sorbitan monolaurate, sorbitan trioleate, polyoxyethylene alkyl ether; anionic emulsifying agents such as sodium lauryl sulfate, sodium alkylbenzenesulfonates (e.g. sodium dodecylbenzenesulfonate), sodium dioctylsulfosuccinate; fillers such as calcium carbonate, titanium oxide, stabilizers such as tribasic lead sulfate, calcium stearate, dibutyltin dilaurate, dioctyltin mercaptide; lubricants such as rice wax, stearic acid, cetyl alcohol; plasticizers such as DOP, DBP; chain transfer agents such as mercaptans (e.g. t-dodecyl mercaptan), trichloroethylene, and pH adjusters. In addition to being used for formation of the coating on the inner wall surfaces of the polymerization vessel, the polymer scale preventive agent of the present invention may further be added directly to the polymerization system, whereby a further enhanced effect in preventing deposition of polymer scale can be obtained. In that case, the addition amount of the agent suitably ranges from about 10 to about 1000 ppm based on the total weight of the monomer or monomers charged into the polymerization vessel. At the time of adding the polymer scale preventive agent, care should be taken not to affect adversely the fish eye, bulk specific gravity, particle size distribution or other qualities of the resulting polymeric product. EXAMPLES The present invention will now be described in detail below, with reference to working examples thereof and comparative examples. In the tables below, the experiments bearing a No. marked with * are comparative examples, and the other experiments, bearing a non-marked No., are working examples of the present invention. Preparation Example 1 Preparation of condensation product No. 1 A 2-liter reaction vessel equipped with a reflux condenser was charged with 900 g of methanol and 40 g of 2,6-diaminopyridine as heterocyclic compound, followed by stirring at room temperature to dissolve 2,6-diaminopyridine in methanol. To the methanol solution thus obtained, 60 g of α-naphthoquinone was added as quinone. After heating to 65°C, the reactants in the vessel were reacted at 65°C for 10 hours. After the reaction was over, the reaction system was cooled to give a methanol solution of a condensation product, which is hereinafter referred to as condensation product No. 1. Preparation of condensation product Nos. 2 to 26 Condensation products were prepared in the same manner as in the above preparation of the condensation product No. 1 except for using the heterocyclic compound having at least two amino groups (A) and quinone compound (B) given in Table 1 and the solvent shown in Table 2. Total concentration of (A)+(B), weight ratio of (A):(B), reaction temperature and reaction time are also set forth in Table 2. Condensation product No. (A) (B) 1 2,6-Diaminopyridine α-Naphthoquinone 2 ― α-Naphthoquinone 3 2,6-Diaminopyridine ― 4 2,6-Diaminopyridine p-Benzoquinone 5 2,6-Diaminopyridine 2-hydroxy-1,4-naphthalene dione 6 2,6-Diaminopyridine β-Naphthoquinone 7 2,6-Diaminopyridine α-Naphthoquinone 8 2,6-Diaminopyridine α-Naphthoquinone 9 3,6-Diaminoacridine p-Benzoquinone 10 3,6-Diaminoacridine α-Naphthoquinone 11 1,6-Diaminoacridine α-Naphthoquinone 12 3,9-Diaminoacridine p-Benzoquinone 13 4,9-Diamino-2-hydroxyacridine 2-hydroxy-1,4-naphthalene dione 14 4,9-Diaminoacridine-2-sulfonic acid p-Benzoquinone 15 2,4-Diamino-6-hydroxypyrimidine α-Naphthoquinone 16 2,4-Diamino-6-hydroxypyrimidine p-Benzoquinone 17 4,6-Diaminopyrimidine α-Naphthoquinone 18 2,4,5-Triaminopyrimidine β-Naphthoquinone 19 2,4-Diaminopyrimidine-5-carboxylic acid 2-hydroxy-1,4-naphthalene dione 20 4,6-Diaminopyrimidine-2-sulfonic acid α-Naphthoquinone 21 2,4-Diaminothiazole α-Naphthoquinone 22 2,4-Diaminothiazole-5-carboxylic acid α-Naphthoquinone 23 2,5-Diaminobenzothiazole p-Benzoquinone 24 5,8-Diaminoquinoline p-Benzoquinone 25 5,8-Diaminoquinoline p-Benzoquinone 26 4,8-Diaminoquinoline α-Naphthoquinone Condensation product No. Total conc. of (A)+(B) (wt. %) (A):(B) (wt. ratio) Solvent Reaction temperature (°C) Reaction time (hour) 1 10 1 : 1.5 Methanol 65 10 2 10 ― Methanol 65 10 3 10 ― Methanol 65 10 4 10 1 : 0.5 Methanol 65 10 5 20 1 : 1 Ethanol 80 10 6 10 1 : 1.5 Methanol 65 20 7 10 1 : 3 Methanol 65 20 8 3 1 : 3 Methanol 65 40 9 2 1 : 1 Ethanol 65 10 10 2 1 : 2 Ethanol 65 10 11 2 1 : 1.5 Ethanol 65 10 12 2 1 : 0.5 Ethanol 65 40 13 1 1 : 1 Ethanol 80 20 14 2 1 : 1 Ethanol 65 10 15 10 1 : 1 Methanol 65 10 16 10 1 : 2 Methanol 65 10 17 10 1 : 1.5 Methanol 65 10 18 10 1 : 0.5 Methanol 65 40 19 20 1 : 1 Ethanol 80 20 20 10 1 : 1 Methanol 65 10 21 10 1 : 1.5 Methanol 65 10 22 10 1 : 3 Methanol 65 10 23 5 1 : 0.5 Ethanol 65 20 24 10 1 : 1.5 Methanol 65 10 25 10 1 : 3 Methanol 65 10 26 5 1 : 0.5 Ethanol 65 20 Example 1 (Experiment Nos. 101 to 126) In each experiment, a stainless-steel polymerization vessel having an internal capacity of 1000 liters and equipped with a stirrer was used to carry out polymerization. In preparing a polymer scale preventive agent in each experiment, the condensation product (F), water-soluble polymeric compound (C), inorganic colloid (D), alkali metal silicate (E), alkaline compound and solvent set forth in Table 3 were used in such amounts as to produce the solvent composition, total concentration of (F)+(C)+(D)+(E), weight ratio of (F):(C):(D):(E), and pH shown in Table 4. The inorganic colloids (a to g, in Tables 3 and 7) which were used as component (D) in this example and Example 2 described below are shown in Table 6. In each experiment, the polymer scale preventive agent prepared as above was applied to the inner wall of the polymerization vessel and to the stirring shaft, stirring blades and the like parts with which the monomer comes into contact during polymerization. The polymer scale preventive agent thus applied was dried by heating at 40°C for 15 minutes to form a coating, followed by washing with water. Subsequently, in each experiment, polymerization was conducted as follows. The polymerization vessel provided with the coating by the coating treatment as above was charged with 400 kg of water, 200 kg of vinyl chloride, 250 g of partially saponified polyvinyl alcohol, 25 g of hydroxypropyl methyl cellulose and 70 g of 3,5,5-trimethylhexanoyl peroxide, followed by polymerization with stirring at 66°C for 6 hours. After the polymerization was finished, the polymeric product and unreacted monomer were recovered, and the inside of the polymerization vessel was washed with water to remove residual resin. Thereafter, the above process including the polymerization and the washing of the inside of polymerization vessel with water was repeated batchwise, without carrying out the coating operation, the repetition number of batch being given in Table 5. After the final batch was over, the amount of polymer scale deposited on areas located in the liquid-phase region and that on areas around the interface between gas and liquid phases inside the polymerization vessel were determined according to the method described below. The results are given in Table 5. - Measurement of the amount of polymer scale deposited The scale deposited in an area of 10 cm square at a predetermined location on the inner wall of a polymerization vessel is scraped off with a stainless steel spatula as completely as can be confirmed with the naked eye, and then the scraped scale is weighed on a balance. The measured value is multiplied by 100 to obtain the amount of the deposited polymer scale per area of 1 m 2 . Besides, the number of fish eyes appearing upon formation of a polymer into a sheet was measured with respect to the polymers obtained in the experiments, according to the method below. The results are given in Table 5. - Measurement of fish eyes A hundred (100) parts by weight of a polymer obtained, 50 parts by weight of dioctyl phthalate (DOP), 1 part by weight of dibutyltin dilaurate, 1 part by weight of cetyl alcohol, 0.25 part by weight of titanium oxide and 0.05 part by weight of carbon black are mixed. The resulting mixture is kneaded at 150°C for 7 minutes with 15,24 cm rolls,and then formed into a sheet 0.2 mm thick. The obtained sheet is examined for the number of fish eyes per 100 cm 2 by light transmission. Further, measurement of luminosity index (L value) of a sheet formed from a polymer was carried out, according to the method below, with respect to the polymers produced in the experiments. The results are given in Table 5. - Measurement of luminosity index (L value) A hundred (100) parts by weight of the obtained polymer, 1 part by weight of a tin laurate stabilizing agent (TS-101, product of Akisima Chemical Co.) and 0.5 part by weight of a cadmium stabilizing agent (C-100J, product of Katsuta Kako Co.), and 50 parts by weight of dioctyl phthalate as a plasticizer are kneaded at 160°C for 5 minutes with a twin roll mill, and then formed into a sheet 1 mm thick. Subsequently, this sheet is placed in a mold measuring 4 x 4 x 1.5 cm, heated at 160°C under a pressure of 65 to 70 kgf/cm 2 for 0.2 hour and press molded under the same conditions to prepare a test specimen. This test specimen is measured for luminosity index L in the Hunter's color difference equation described in JIS Z 8730 (1980). The greater the value of L, the higher the whiteness evaluated, namely, the slighter the initial coloration evaluated. The value of L is determined as follows. The stimulus value Y of XYZ color system is determined by the photoelectric tristimulus colorimetry using the standard light C, photoelectric colorimeter (Color measuring color difference meter Model Z-1001DP, product of Nippon Denshoku Kogyo K.K.) in accordance with JIS Z 8722. As the geometric condition of illumination and light reception, the condition d defined in section 4.3.1 of JIS Z 8722 is adopted. From the stimulus value Y obtained, the L value is calculated based on the equation: L=10Y 1/2 described in JIS Z 8730 (1980). Exp. No. Polymer scale preventive agent (F) Condensation product No. (C) Water-soluble polymeric compound (D) Inorganic colloid (E) Alkali metal silicate 101 1 Gelatin b ― 102 2 Gelatin b ― 103 3 Gelatin b ― 104 4 Polyacrylic acid c ― 105 5 Na salt of carboxymethyl cellulose a ― 106 6 ― ― ― 107 7 Polyvinyl alcohol d ― 108 8 Polyvinyl pyrrolidone ― sodium methasilicate 109 9 Gelatin b ― 110 10 Polyacrylic acid c ― 111 11 Na salt of carboxymethyl cellulose a ― 112 12 ― ― ― 113 13 Polyvinyl alcohol d ― 114 14 Polyvinyl pyrrolidone ― sodium methasilicate 115 15 Gelatin b ― 116 16 Polyacrylic acid c ― 117 17 Na salt of carboxymethyl cellulose a ― 118 18 ― ― ― 119 19 Polyvinyl alcohol d ― 120 20 Polyvinyl pyrrolidone ― sodium methasilicate 121 21 Gelatin a ― 122 22 Polyvinyl pyrrolidone d ― 123 23 ― ― ― 124 24 Gelatin a ― 125 25 Polyvinyl pyrrolidone d ― 126 26 ― ― ― Exp. No. Polymer scale preventive agent Total conc. of (F)+(C) +(D)+(E) (wt. %) (F):(C):(D):(E) (weight ratio) Alkaline compound (pH) Solvent (weight ratio) 101 0.3 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 102 0.3 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 103 0.3 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 104 0.3 100: 50:100: ― NaOH (10.0) Water:Methanol (90:10) 105 0.3 100: 50:200: ― KOH (11.0) Water:Methanol (90:10) 106 0.5 ― Ethylenediamine (11.0) Water:Methanol (90:10) 107 0.5 100:100:200: ― NaOH (11.0) Water:Methanol (90:10) 108 0.5 100:100:― :300 NaOH (11.0) Water:Acetone (90:10) 109 0.3 100:100:100: ― NaOH (10.0) Water:Ethanol (70:30) 110 0.3 100: 50:100: ― NaOH (10.0) Water:Ethanol (90:10) 111 0.3 100: 50:200: ― KOH (11.0) Water:Ethanol (90:10) 112 0.5 ― Ethylenediamine (11.0) Water:Ethanol (90:10) 113 0.5 100:100:200: ― NaOH (11.0) Water:Ethanol (90:10) 114 0.5 100:100:― :300 NaOH (11.0) Water:Ethanol (90:10) 115 0.3 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 116 0.3 100: 50:100: ― NaOH (10.0) Water:Methanol (90:10) 117 0.3 100: 50:200: ― KOH (11.0) Water:Methanol (90:10) 118 0.5 ― Ethylenediamine (11.0) Water:Methanol (90:10) 119 0.5 100:100:200: ― NaOH (11.0) Water:Methanol (90:10) 120 0.5 100:100:― :300 NaOH (11.0) Water:Acetone (90:10) 121 0.5 100:100:100: ― NaOH (11.0) Water:Methanol (70:30) 122 0.5 100: 50:200: ― NaOH (11.0) Water:Methanol (80:20) 123 0.5 ― Ethylenediamine (11.5) Water:Methanol (90:10) 124 0.5 100:100:100: ― NaOH (11.0) Water:Methanol (70:30) 125 0.5 100: 50:200: ― NaOH (11.0) Water:Methanol (80:20) 126 0.5 ― Ethylenediamine (11.5) Water:Methanol (90:10) Exp. No. Repetition number of batch Results of polymerization Polymer scale amount (g/m 2 ) Number of fish eyes Luminosity index (L) Liquid phase Around interface between gas and liquid phases 101 3 0 6 16 73.0 102 2 18 100 39 73.0 103 2 22 90 37 73.0 104 4 0 8 17 73.0 105 3 0 6 15 73.0 106 2 0 20 21 73.0 107 3 0 7 16 73.0 108 5 0 6 15 73.0 109 3 0 8 18 73.0 110 4 0 10 20 73.0 111 3 0 8 18 73.0 112 2 0 25 30 73.0 113 3 0 8 20 73.0 114 5 0 8 20 73.0 115 3 0 8 18 73.0 116 4 0 10 19 73.0 117 3 0 10 18 73.0 118 2 0 20 23 73.0 119 3 0 8 18 73.0 120 5 0 8 18 73.0 121 3 0 9 18 73.0 122 3 0 8 16 73.0 123 3 1 25 26 73.0 124 3 0 8 16 73.0 125 3 0 7 14 73.0 126 3 1 22 30 73.0 Inorganic colloid Diameter of colloidal particles Name of article Manufacturer a 10 ∼ 20 mµ Snowtex 0 (colloidal silica) Nissan Chemical Industries, Ltd. b 5 ∼ 7 mµ Snowtex CXS-9 (colloidal silica) Nissan Chemical Industries, Ltd. c 100 ∼ 200 mµ Titanium oxide Nissan Chemical Industries, Ltd. d 10 ∼ 20 mµ Aluminum oxide Nissan Chemical Industries, Ltd. e 60 ∼ 70 mµ Zirconium oxide Nissan Chemical Industries, Ltd. f 20 ∼ 50 mµ Tin oxide Nissan Chemical Industries, Ltd. g 10 ∼ 15 mµ Iron hydroxide produced by the present inventors Example 2 (Experiment No. 201 to 226) In each experiment, a stainless-steel polymerization vessel having an internal capacity of 20 liters and equipped with a stirrer was used for polymerization. In preparation of a polymer scale preventive agent in each experiment, the condensation product (F), water-soluble polymeric compound (C), inorganic colloid (D), alkali metal silicate (E), alkaline compound and solvent set forth in Table 7 were used in such amounts as to produce the solvent composition, total concentration of (F)+(C)+(D)+(E), weight ratio of (F):(C):(D):(E), and pH given in Table 8. The polymer scale preventive agent thus prepared was applied to the inner wall of the polymerization vessel and to the stirring shaft, stirring blades and the like areas with which the monomer comes into contact during polymerization. The polymer scale preventive agent applied was dried by heating at 40°C for 15 minutes to form a coating, followed by washing the inside of the polymerization vessel with water. Subsequently, in each experiment, polymerization was carried out as follows. The polymerization vessel provided with the coating as above was charged with 9 kg of water, 225 g of sodium dodecylbenzenesulfonate, 12 g of t-dodecyl mercaptan and 13 g of potassium peroxodisulfate. The inside atmosphere of the polymerization vessel was replaced with nitrogen gas, thereafter 1.3 kg of styrene and 3.8 kg of butadiene were charged into the vessel, and polymerization was carried out at 50°C for 20 hours. After the polymerization was completed, the polymeric product and unreacted monomers were recovered, followed by washing the inside of the vessel with water to remove residual resin. Thereafter, the above process including the polymerization and the washing of the inside of polymerization vessel with water was repeated batchwise, without carrying out the coating operation, the repetition number of batch being given in Table 9. After the final batch was over, the amount of polymer scale deposited on areas located in the liquid-phase region and that on areas around the interface between gas and liquid phases inside the polymerization vessel were determined according to the same method as in Example 1. The results are given in Table 9. Besides, measurement of luminosity index (L value) of a sheet formed from a polymer was carried out with respect to each of the polymers produced in the experiments, according to the method below. The results are given in Table 9. - Measurement of luminosity index (L value) To 1 kg of the polymer latex obtained was added 1 kg of 2% magnesium sulfate solution to cause aggregation and sedimentation. The sediment was filtered off, washed with a hot water at 80 to 90°C twice or three times and dried at 40°C for 25 hours in a vacuum dryer to give a resin. The resin was placed in a mold measuring 9 x 9 x 0.1 cm (depth), heated at 195°C under a pressure of 50 to 60 kgf/cm 2 for 0.2 hour and press molded under a final pressure of 80 kgf/cm 2 to prepare a test specimen. This test specimen was measured for luminosity index L in the same manner as in Example 1. Exp. No. Polymer scale preventive agent (F) Condensation product No. (C) Water-soluble polymeric compound (D) Inorganic colloid (E) Alkali metal silicate 201 1 Polyacrylic acid b ― 202 2 Polyacrylic acid b ― 203 3 Polyacrylic acid b ― 204 4 Sodium alginate e ― 205 5 Polyvinyl pyrrolidone f ― 206 6 Polyvinyl pyrrolidone g ― 207 7 ― ― ― 208 8 Gelatin ― Water glass 209 9 Polyacrylic acid b ― 210 10 Sodium alginate e ― 211 11 Polyvinyl pyrrolidone f ― 212 12 Polyvinyl pyrrolidone g ― 213 13 ― f ― 214 14 Gelatin ― Water glass 215 15 Polyacrylic acid b ― 216 16 Sodium alginate e ― 217 17 Polyvinyl pyrrolidone f ― 218 18 Polyvinyl pyrrolidone g ― 219 19 ― ― ― 220 20 Gelatin ― Water glass 221 21 Polyacrylic acid e ― 222 22 Pectin b ― 223 23 Casein ― Water glass 224 24 Polyacrylic acid e ― 225 25 Pectin b ― 226 26 Casein ― Water glass Exp. No. Polymer scale preventive agent Total conc. of (F)+(C) +(D)+(E) (wt. %) (F):(C):(D):(E) (weight ratio) Alkaline compound (pH) Solvent (weight ratio) 201 0.5 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 202 0.5 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 203 0.5 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 204 0.5 100:100:200: ― NaOH (10.0) Water:Methanol (70:30) 205 0.5 100:100:300: ― NaOH (10.0) Water:Methanol (70:30) 206 0.5 100: 50:100: ― KOH (10.5) Water:Methanol (70:30) 207 0.5 ― Ethylenediamine (10.5) Water:Methanol (90:10) 208 0.5 100:200:― :100 Ethylenediamine (11.0) Water:Methanol (90:10) 209 0.5 100:100:100: ― NaOH (10.0) Water:Ethanol (70:30) 210 0.5 100:100:200: ― NaOH (10.0) Water:Ethanol (70:30) 211 0.5 100:100:300: ― NaOH (10.0) Water:Ethanol (70:30) 212 0.5 100: 50:100: ― KOH (11.0) Water:Ethanol (70:30) 213 0.5 ― Ethylenediamine (11.0) Water:Ethanol (90:10) 214 0.5 100:200:100: ― Ethylenediamine (11.0) Water:Ethanol (90:10) 215 0.5 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 216 0.5 100:100:100: ― NaOH (10.0) Water:Methanol (70:30) 217 0.5 100:100:300: ― NaOH (10.0) Water:Methanol (70:30) 218 0.5 100:100:100: ― KOH (11.0) Water:Methanol (70:30) 219 0.5 ― Ethylenediamine (11.0) Water:Methanol (90:10) 220 0.5 100:200:― :100 Ethylenediamine (11.0) Water:Methanol (90:10) 221 0.5 100:100:100: ― NaOH (12.0) Water:Methanol (70:30) 222 0.5 100:100:200: ― NaOH (12.0) Water:Methanol (70:30) 223 0.5 100: 50:― :200 Ethylenediamine (11.5) Water:Methanol (70:30) 224 0.5 100:100:100: ― NaOH (12.0) Water:Methanol (70:30) 225 0.5 100:100:200: ― NaOH (12.0) Water:Methanol (70:30) 226 0.5 100: 50:200: ― Ethylenediamine (11.5) Water:Methanol (70:30) Exp. No. Repetition number of batch Results of polymerization Polymer scale amount (g/m 2 ) Luminosity index (L) Liquid phase Around interface between gas and liquid phases 201 2 0 5 85.0 202 1 20 150 85.0 203 1 26 160 85.0 204 2 0 4 85.0 205 2 0 2 85.0 206 2 0 5 85.0 207 1 0 15 85.0 208 2 0 4 85.0 209 2 0 4 85.0 210 2 0 3 85.0 211 2 0 1 85.0 212 2 0 3 85.0 213 1 0 8 85.0 214 2 0 3 85.0 215 2 0 8 85.0 216 2 0 8 85.0 217 2 0 6 85.0 218 2 0 6 85.0 219 1 0 20 85.0 220 2 0 8 85.0 221 2 0 9 85.0 222 2 0 7 85.0 223 2 0 4 85.0 224 2 0 8 85.0 225 2 0 6 85.0 226 2 0 3 85.0 Example 3 (Experiment Nos. 301 to 305) In each experiment, a stainless-steel polymerization vessel having an internal capacity of 20 liters and equipped with a stirrer was used to carry out polymerization. In each experiment, a polymer scale preventive agent (the one used in the experiment whose number (No.) is shown in Table 10) was applied to the inner wall of the polymerization vessel and to the stirring shaft, stirring blades and the like parts with which monomers come into contact during polymerization. The agent applied was dried by heating at 50°C for 15 minutes to form a coating, followed by washing with water. Thereafter, in each experiment, polymerization was carried out as follows. The polymerization vessel provided with the coating as above was charged with 40 kg of water and 6 g of sodium dodecylbenzenesulfonate, and temperature was raised to 60°C with stirring. After the gas phase in the polymerization vessel was replaced with nitrogen gas, the vessel was further charged with 94 g of n-butyl acrylate, 220 g of methyl methacrylate, 5 g of acrylic acid and 5 g of methacrylic acid. Subsequently, 1 g of ammonium persulfate and 1 g of sodium hydrosulfite were charged into the polymerization vessel, and the resulting mixture in the vessel was stirred at 60°C for 20 minutes. Furthermore, into the polymerization vessel were added a monomeric mixture (prepared by mixing 2.1 kg of n-butyl acrylate, 4.8 kg of methyl methacrylate, 100 g of acrylic acid and 100 g of methacrylic acid), 500 g of an aqueous 1 wt.% ammonium persulfate solution, 500 g of an aqueous 1 wt.% sodium hydrosulfite solution and 2.0 kg of an aqueous 25 wt.% polyoxyethylene nonyl phenyl ether solution, evenly over a 3-hour period. After the addition was completed, the polymerization vessel was heated to 70°C and polymerization was carried out for 2 hours. After the polymerization was over, the resulting polymeric product and unreacted monomers were recovered, and the inside of the vessel was washed with water to remove residual resin. Thereafter, a batch of operations from the formation of the coating through polymerization to the washing of the inside of the polymerization vessel with water as above-described was repeated 50 times. Upon the 50th batch, the amount of polymer scale deposited on areas located in the liquid-phase region and that on areas around the interface between gas and liquid phases inside the polymerization vessel were measured in the same manner as in Example 1. The results are given in Table 10. Exp. No. Polymer scale preventive agent (Exp. No.) Repetition number of batch Results of polymerization Polymer scale amount (g/m 2 ) Liquid phase Around interface between gas and liquid phases 301 201 50 0 30 302 209 50 0 35 303 215 50 0 42 304 221 50 0 30 305 224 50 0 30 Example 4 (Experiment Nos. 401 to 405) In each experiment, a stainless-steel polymerization vessel having an internal capacity of 100 liter and equipped with a stirrer was used for polymerization. In each experiment, a polymer scale preventive agent (the one used in the experiment whose number (No.) is shown in Table 11) was applied to the inner wall of the polymerization vessel and to the stirring shaft, stirring blades and the like parts with which monomers come into contact during polymerization. The agent applied was dried by heating at 50°C for 15 minutes to form a coating, followed by washing with water. Subsequently, in each experiment, the polymerization vessel thus provided with the coating was charged with 40 kg of water, 500 g of disproportionated potassium rhodinate, 13 kg of polybutadiene latex (solid content: 45%), 9 kg of styrene monomer, 5 kg of acrylonitrile monomer, 40 g of t-dodecyl mercaptan and 140 g of cumene hydroperoxide. Then, with the temperature inside the polymerization vessel maintained at 47°C, 200 g of grape sugar, 2 g of ferrous sulfate and 100 g of sodium pyrophosphate were charged into the vessel, and polymerization was carried out with stirring at 65°C for 4 hours. After the polymerization was over, the polymeric product and unreacted monomers were recovered, and the inside of the polymerization vessel was washed with water to remove residual resin. Thereafter, a batch of operations from the formation of the coating through polymerization to the washing of the inside of the polymerization vessel with water as above-described was repeated 80 times. Upon the 80th batch, the amount of polymer scale deposited on areas located in the liquid-phase region and that on areas around the interface between gas and liquid phases inside the polymerization vessel were measured in the same manner as in Example 1. The results are given in Table 11. Exp. No. Polymer scale preventive agent (Exp. No.) Repetition number of batch Results of polymerization Polymer scale amount (g/m 2 ) Liquid phase Around interface between gas and liquid phases 401 204 80 0 60 402 210 80 0 66 403 216 80 0 80 404 222 80 0 70 405 225 80 0 45

Claims: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond on the basis of a condensation product of a heterocyclic compound having at least two amino groups, and a quinone compound, characterized by an alkaline solution with a pH of 7.5 to 13.5 containing a mixed solvent of water with an organic solvent miscible with water, said organic solvent being present in an amount of not more than 50% by weight based on said mixed solvent, and containing the condensation product prepared by a reaction of the heterocyclic compound with the quinone compound in a suitable solvent at a temperature of room temperature to 200°C for 0.5 to 100 hours. The agent of Claim 1, characterized by an alkaline solution with a pH of 8 to 13.5. The agent of Claim 1, wherein the condensation product is obtained from a compound having the following general formula (1): (R 1 ) k X(NH 2 ) 2 wherein R 1 is -OH, -COOH, -SO 3 H, -NH 2 , -Cl, -Br, -I, -SH, -NO 2 , -COCH 3 , -OCH 3 , -N(CH 3 ) 2 , -C 6 H 5 or an alkyl group having 1 to 3 carbon atoms, and where a plurality of R 1 groups are present, they may be the same or different from each other, k is an integer of 0 to 9, and X is a heterocyclic group with a valence of k+2. The agent of Claim 3, wherein X in the general formula (1) is a group derived from a compound selected from the group consisting of pyrrole, indole, isoindole, carbazole, porphyrin, oxazole, thiazole, benzothiazole, imidazole, pyrazole, triazole, thiadiazole, pyridine, pyrimidine, quinoline, acridine, phenanthridine, phenanthroline, naphthyridine, furan, benzofuran, pyran, pyrrone, benzopyrylium, cumarin and xanthone, by removal of k+2 hydrogen atoms attached to a ring of said compound. The agent of Claim 1, wherein the heterocyclic compound comprises at least one compound which is selected from the group consisting of pyridine compounds, acridine compounds, pyrimidine compounds, thiazole compounds and quinoline compounds and which has at least two amino groups. The agent of Claim 1, wherein the heterocyclic compound comprises at least one compound selected from the group consisting of 2,6-diaminopyridine, 3,6-diaminoacridine, 1,6-diaminoacridine, 3,9-diaminoacridine, 4,9-diamino-2-hydroxyacridine, 4,9-diaminoacridine-2-sulfonic acid, 2,4-diamino-6-hydroxypyrimidine, 4,6-diaminopyrimidine, 2,4,5-triaminopyrimidine, 2,4-diaminopyrimidine-5-carboxylic acid, 4,6-diaminopyrimidine-2-sulfonic acid, 2,4-diaminothiazole, 2,4-diaminothiazole-5-carboxylic acid, 5,8-diaminoquinoline and 4,8-diaminoquinoline. The agent of Claim 1, wherein the quinone compound comprises at least one compound selected from the group consisting of: the compounds having the following general formula (2): wherein (R 2 )'s may be the same or different and each are -H, -NH 2 , -Cl, -Br, -OH, -NO 2 , -COCH 3 , -OCH 3 , -N(CH 3 ) 2 , -COOH, -SO 3 H or an alkyl group having 1 to 3 carbon atoms; the compounds having the following general formula (3): wherein (R 2 )'s may be the same or different and each are as defined above; the compounds having the following general formula (4): wherein (R 2 )'s may be the same or different and each are as defined above, and (R 3 )'s may be the same or different and each are -H, -Cl, -Br, -OH, -COCH 3 , -OCH 3 , -CH 3 , -COOH or -SO 3 H; and the compounds having the following general formula (5): wherein (R 2 )'s may be the same or different and each are as defined above, and (R 3 )'s may be the same or different and each are as defined above. The agent of Claim 1, wherein the quinone compound comprises at least one compound selected from the group consisting of o- and p-benzoquinones, α-naphthoquinone, β-naphthoquinone and 2-hydroxy-1,4-naphthalenedione. The agent of Claim 1, wherein the condensation product comprises one which is obtained by condensing 1 part by weight of the heterocyclic compound with 0.1 to 5 parts by weight of the quinone compound. The agent of Claim 1, further comprising at least one member selected from the group consisting of a water-soluble polymeric compound, and inorganic colloid, and an alkali metal silicate. The agent of Claim 10, wherein the at least one member is a combination of the water-soluble polymeric compound with an inorganic colloid, or a combination of the water-soluble polymeric compound with an alkali metal silicate. The agent of Claim 1, wherein the concentration of the condensation product is 0.001 to 5% by weight. A polymerization vessel for polymerizing a monomer having an ethylenically unsaturated double bond on the basis of a condensation product of a heterocyclic compound having at least two amino groups, and a quinone compound, characterized by a coating on its inner wall surfaces, wherein said coating has been formed by applying an alkaline solution with a pH of 7.5 to 13.5 containing a mixed solvent of water with an organic solvent miscible with water, said organic solvent being present in an amount of not more than 50% by weight based on said mixed solvent, and containing a condensation product prepared by a reaction of the heterocyclic compound with the quinone compound in a suitable solvent at a temperature of room temperature to 200°C for 0.5 to 100 hours, followed by drying. The polymerization vessel according to Claim 13, characterized in that the coating has been formed by applying an alkaline solution having a pH of 8 to 13.5. The polymerization vessel of Claim 13 or 14, wherein said coating is further formed on the other areas than the inner wall with which the monomer comes into contact. The polymerization vessel of Claim 13 or 14, wherein said coating is further formed on the areas with which unreacted monomers come into contact of a system for recovering unreacted monomers. The polymerization vessel of Claim 13 or 14, wherein the coating has a coating weight after dried of 0.001 to 5 g/m 2 . The polymerization vessel according to any of Claims 13 to 17, characterized in that the coating has been formed from an agent containing as at least one member of a combination of the component of the water-soluble polymeric compound with an inorganic colloid or a combination of the water-soluble poylmeric compound with an alkali metal silicate. A process for producing a polymer of a monomer having an ethylenically unsaturated double bond on the basis of a condensation product of a heterocyclic compound having at least two amino groups, and a quinone compound, characterized by polymerizing the monomer in a polymerization vessel having a coating on its inner wall surfaces, wherein said coating has been formed by applying an alkaline solution with a pH of 7.5 to 13.5, followed by drying. The process of Claim 19, characterized in that the coating is formed by applying an alkaline solution having a pH from 8 to 13.5. The process of Claim 19 or 20, wherein said polymerization is conducted as a suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization, or gas phase polymerization. The process of Claim 19 or 20, wherein said monomer comprises at least one compound selected from the group consisting of vinyl halides; vinyl esters; acrylic acid, methacrylic acid, and their esters and anhydrides; diene monomers; styrene; acrylonitrile; vinylidene halides; and vinyl ethers.

Inventors: SHIMIZU TOSHIHIDE, WATANABE MIKIO, SHIMIZU, TOSHIHIDE, WATANABE, MIKIO
Applicants: SHINETSU CHEMICAL CO, SHIN-ETSU CHEMICAL CO., LTD.
Application year: 1994
Main classification: C08F2
IPC codes: C08F2, B01J19